Rallus minutus Alcover, Pieper, Pereira & Rando, 2015, new species

Rallus minutus, new species

São Jorge rail

[Figures 7, 8 I, 9C, 10D, 11E, 12D, 13C, 14C, 15E, 16E, 17E] Artistic reconstruction: Figure 23

Holotype: MCMa 1950.014, associated skeleton (pmx frags, ste frag, LR cors, R scap frag, L hum, uln and uln frag, L cmc, fem frags, tbt and tbt frags, R tmt and prox L tmt, 3 ped phas).

Measurements of holotype (in mm): Humerus—length: 25.6; proximal width: 5.6; minimum shaft width: 1.5; distal width: 4.1. Ulna—length: 17.6; proximal width: 2.5; proximal diameter: 2.4; minimum shaft width: 1.3; distal width: 2.4. Carpometacarpus—length: 11.0; proximal width: 3.4. Femur—proximal width: 5.9; minimum shaft width: 2.2; distal width: 5.7. Tibiotarsus—minimum shaft width: 2.2; distal width: 5.0. Tarsometatarsustotal length: 27.3; proximal width: 5.0; minimum shaft width: 2.5; distal width: 5.5. Scapula—proximal width: 3.6. Coracoid—length: 13.5.

Type locality: Gruta do Pasto do Engenheiro, São Jorge, collected 20 Sept 2014.

Known distribution: São Jorge, Central Azores.

Collectors: all the material was collected on 16–20 Sept 2014 by ET, FP, OT, DS and JAA.

Paratypes: Gruta da Beira: MCMa 1951.014, associated skeleton (pmx frag, man frag, ste frag, L cor, prox L uln, L hum, fem frags, R tbt, L tbt frag, LR tmt, 5 vert); MCMa 1952.014, associated skeleton (pmx frags, dist R tbt, distal R tmt, verts); MCMa 1953.014, associated skeleton (pmx frag, dis R hum, dis R tbt, tmt frag); MCMa 1954.014, associated skeleton (sku frag, pmx frag, man frag, LR fem, 2 LR tbt, LR tmt, 4 verts, 8 phas); MCMa 1955.014, associated skeleton (sku frags, man frag, pmx frags, femur frag, tbt frags, R and dis L tmt, syn frag,, 5 verts, 7 ped phas); MCMa 1956.014, associated material corresponding to two individuals (L uln, prox R fem, tbt frags, LR tmt, tmt frags, syn, 3 ped phas); MCMa 1959.014, associated skeleton (sku, man, dis L tmt, prox L tbt, sha L fem).

Gruta do Pasto do Engenheiro: MCMa 1957.014, associated skeleton (sku frag, fem frags, tbt and tbt frags, tmt frags, syn frag, pha); MCMa 1958.014, associated skeleton (prox R tbt, R tmt, pha).

Measurements of paratypes: see Table 1.

Age: Probably Holocene-Recent.

Diagnosis. A very small species of Rallus. It is smaller than any other rail from Macaronesia and markedly smaller than R. aquaticus. The wing bones are relatively more reduced than in any other Azorean rail, including the São Miguel rail. The bill is very elongated and slightly curved. The humerus has a reduced fossa pneumotricipitalis, the crista bicipitalis is less expanded than in R. aquaticus, and has a reduced and relatively flattened caput. All the bones, especially ulna, carpometacarpus and tarsometatarsus are very reduced in size relative to R. aquaticus (Figures 12, 13 and 17). The tarsometatarsus is relatively stout (Figure17). The synsacrum (Figure 14) is very broad, and the sternum (Figure 10) presents a very reduced depth to the carina sterni (the most reduced carina recorded among the species described herein).

Etymology. from the Latin, meaning little.